Artificial Equilibrium Orbital Configurations by Means of Continuous Thrust

Abstract

Keplerian dynamics usually dictates the orbital configuration for a space mission. The fulfillment of special requirements, however, could demand that a spacecraft maintains a certain distance from the position of Keplerian equilibrium. This can be true for low Earth orbits and for three-body problems. The natural equilibrium position can be occupied by another satellite or it can be simply a reference orbiting point. Such a non-keplerian configuration, also called artificial equilibrium, can be maintained only if continuous thrust — provided by low specific impulse motors or solar sails — is applied. In the present paper, the maps identifying the equi-thrust regions for the two- and the three-body problem are reported. Once the space regions requiring a defined value of the thrust (in module) are detected, a control strategy for moving from an artificial equilibrium to a different one without changing the thrust level is proposed. In such an approach, therefore, the orbital maneuver is accomplished by means of an attitude change only, allowing for a remarkable simplification of the guidance and control systems.